Automatic slack adjusting mechanism



Aug. 18, 1953 K. B. M DOUGALL 2,648,996

AUTOMATIC SLACK ADJUSTING MECHANISM Filed Nov. 8, 1950 4 Sheets-Sheet l V r 50/ 67 2 10? 4 INVENTOR 101 Jfir/r/and fi Alacfioz gall BY W t @W/ ATTORNEYJ Aug. 18, 1953 K. B. M DOUGALL AUTOMATIC SLACK ADJUSTING MECHANISM 4 Sheets-Sheet 2 Filed NOV. 8, 1950 1 m d w W W m C M m d 0 2 m M w 4 5 M3 8 W 7 2 I /q w 9 111 Z w 6 5 8 v w rwwdfl u o w m ATTORNEYJ Aug. 18, 1953 K. B. M DOUGALL AUTOMATIC SLACK ADJUSTING MECHANISM 4 Sheets-Sheet 3 Filed Nov. 8, 1950 ATTORNEYS Aug. 18, 1953 K. B. M DOUGALL AUTOMATIC SLACK ADJUSTING MECHANISM 4 Sheets-Sheet 4 Filed NOV. 8, 1950 BY aw) I71 ATTORNEYJ' Patented Aug. 18, 1953 AUTOMATIC SLACK ADJUSTING MECHANISM Kirkland B. MacDougall, Benton, Pa.

Application November 8, 1950, Serial No. 194,658,

6 Claims.

This invention relates to automatic adjusting mechanism or devices. The adjusting devices are particularly adapted for brakes of automotive vehicles such as trucks, buses, trailer trucks, etc.

The adjusting devices are self-contained and unitary and are adapted to be associated with each of the brake bands of the brakes of the vehicle. Each device is actually mounted on and carried by the cam shaft of the braking mechanism and is adapted to automatically properly adjust each of the brake bands of the braking system of the vehicle individually when wear has occurred and the adjustment in this connection is positive and means are provided so that, automatically, an adjustment of the brake bands will 1 be prevented unless actual wear of one or more .of the bands of the brakes of the vehicle has occurred. Each of the adjusting devices is so {constructed that the adjusting cycle of the brakes ;is prevented when the brakes are in a braking position.

Additionally, there is provided an adjusting feature of the device that provides for automatic brake adjustment with predetermined amounts of travel of a power arm of a pneumatic cylinder or the like, and when the various component parts comprising the device are automatically se- -'curely held in their proper position and coopera- "tive relationship with each other. Additionally, the device is such that the timing cycle of events leading up to and including the automatic ad- ,justment of the brakes is such that the same will occur at the proper time throughout the braking ,stroke and return or releasing stroke. Additionially, the device is so constructed as regards its exterior casing so as to prevent the escape of lubricant and the entrance of dirt and water and other detrimental media into the same.

There are some so-called automatic brake adjusting mechanisms or devices in the prior art which operate fairly satisfactorily but which do not embody structural characteristics and component cooperating elements so as to attain the beneficial and efficacious results as set forth herein with respect to the present invention.

In the present invention, the device is so constructed and the component elements are so arranged in their cooperative relationship that, if the cam shaft should fail to return to a released position, novel means is provided to prevent the return or operation of the device. If this prevention of the return of the adjuster or device were not provided for, under the circumstances, there would be a false adjustment of the brakes .and the same would be tightened and probably prevent the movement of the vehicle.

an important feature of the present invention and something that is not provided for in the prior art devices.

automatic adjusters for the brakes of automotive vehicles and an improvement on the adjusting device or mechanism shown in my Patent 2,481,319, September 6, 1949.

In the present invention, the component and cooperating elements constituting the same are such that the device itself can be preset to accommodate the same to the particular type of vehicle and the particular power stroke that is to be applied to the device for its proper functioning in automatically adjusting the brakes and, additionally, the device is subject to an exterior adjustment to rearrange or move certain of the component elements relative to others so that the presetting may be readily accomplished whether or not the device has actually beenapplied to the cam shaft of the brake operating mechanism.

In view of the foregoing, it is, therefore, an object of the present invention to provide an automatically operating adjusting device for automotive vehicles wherein the device will be prevented from indexing when the cam shaft which operates the brake bands or the like is in a forward or braking position.

Another object of the invention is to provide a completely automatically operating automotive brake adjusting device which is relatively simple as regards the structural features thereof and can be manufactured economically and readily applied to the cam shaft that operates the brakes and preset or adjusted to properly and efliciently perform its adjusting function under all and varying conditions that may exist with different types of automotive vehicles.

Another object of the invention is to provide a brake adjusting device carrying exterior means for adjustment of the various amounts of travel of the power arm which operates the device when it is mounted on the cam shaft that operates the brake-the amount of travel of the power arm adjusted--and the provision of means for securely maintaining the adjusted means in positiononce having been properly located.

Another object of the invention is to provide in a device of the character set forth suitable means for timing the cycle of events leading. up

.to and including adjustment of the brakes or brake so that the same will occur at the proper time throughout the braking stroke and the return or release stroke or position.

This is 55 Another object of the invention is to provide a J unitary and self-contained device wherein the majority of the component elements thereof are encased and the escape of lubricant therefrom and the entrance of water, dirt and other deleterious matter thereinto are prevented.

With the above and other objects in View, the invention consists in the construction and novel combination and arrangement of parts hereinafter fully described, illustrated in the accompanying drawings and pointed out in the claims hereto appended, it being understood that various changes in the form, proportions, and minor details of construction, within the scope of the claims, may be resorted to without departing-from the spirit or sacrificing any of the advantages of the invention In the drawings: I

Fig. 1 is a perspective view showing the brake adjusting device in its operative relationship with the power cylinder and the brake shoes of the vehicle; 3

Fig. 2 is a sectional view taken substantially along the lines 2'2 of Fig. 1, looking in the'dire'ction. of the arrows;

Fig. 3 is a view in perspective of the cover or closure for the device with a part thereof broken away to show detail construction;

Fig. 4 is a view of the casing of the device partly invertical section and partly in fragmentary elevation; Fig. 5 is a longitudinal sectional view taken substantially along the lines 5--5 of Fig. 1, looking in the direction 'of the arrows and showing the adjuster in a. released position;

Fig. (i is a view similar to Fig. 5 but showing the component parts in their braking position;

Fig. 7 is, a sectional view taken substantially along the line 'l.'l of Fig. '1 showing the device in section and the camshaft motor in elevation;

Fig. 8 is. a perspective view of a ratcheting gear and hub structure;

Figs. 9 and 10'are views similar to Figs. 5 and 6. but showing a slight modification or variation of the invention;

Fig. 11 is a perspective view of a ring-gear and v the means associated therewith for preventing the adjusting cycle'while thehub and cam shaft are in'for'ward or braking position and having the slidable pin disassociated therefrom;

Fig. 12 is a View similar to Fig. 11 showing'the pin associated with the ring gear;

Fig. 13 is a fragmentary vie'wlpartly in elevation and partly in section'showing'the'pi'n associated with the ring gear; I v

Fig. 14 is a view in perspective of the cover assembly; 3

Fig. 15 is a view of the cover assembly of'Fig. 14 showing the opposite side thereof;

Fig. 16 is 'a vertical sectional view taken substantially along the line "5-46 of Fig. 15.; and h Fig. 17 is a vertical sectional view taken substantially along the line 11-41 of Fig. 15.

The invention will be more readily understood by referring to the drawings in; detail wherein, in

the several views, the same numerals or characters all denote the same parts.

In Fig. 1, there is more or less diagrammatically shown the two' arcuate brake shoe portions l8 and I!) which, as understood, have'applied thereto any brake lining or other friction surface. The opposite end portions 20 andZ I of the 'brakeshoes are usually flattened to -provide fiat surfaces which are spacedly opposed to each other and, inbetween the same, the brake operating cam 22 is positioned. This camis usually at the outer end of cam shaft 23 which supports and carries the same, while the other end of this cam shaft is suitably formed with longitudinally extending splines 24. Ordinarily, there is a retractible coil spring 25 which normally tends to urge the brake shoes 18 and i9 toward each other. A suitable air chamber 2'5 has the usual power operating arm or piston rod 2'! extending longitudinally outwardly therefrom.

The brake shoes, cam and cam shaft and the power operating air cylinder 26, with its power operating arm 27, are conventional braking elements, in a conventional braking system or systems for automotive vehicles.

My automatically operating brake adjusting mechanism or device is generally indicated at 28 and, as. will be seen from the several figures of the drawings, it is mounted on and carried by the. splined end 24 of the cam shaft 23. The device consists of a hollow casing generally denoted at 29 and this casing is of two parts or split and includes a main casing por iOn 30, and a casing closure portion 3!, each of which is hollow and contain the hereinafter mentioned component and cooperating elements.

The hollow main portion of the casing has a centrally disposed opening 32 in a longitudinal end wall 33 thereof and a cylindrical interior wall 34 and has an open end 35. The lower portion 35 of the casing 30 tapers and is provided, with an interiorly screw threaded opening 31 and the upper portion of the casing has integral there.- with an upstanding, substantially flat and re etangularly shaped arm 38. This arrn, adjacent but inwardly of its extreme upper end '33, is provided with a series of transversely spaced interiorly threaded openings 40, which openings .41! are adapted to receive therein the end portions of exteriorly screw threaded headed bolts 41, which headed bolts extend through transversely spaced openings 42 in the 'lower portion of an adjustable or interchangeable auxiliary arm '43 and the said bolts Al, therefore, adjustably secure the auxiliary arm '43 'to the arm 38.. As shown in Figure 4, there are three openings 40 in the arm 38 which are'threa'd'edas, shown in Figure 2 and three openings 42 in the .arm Two of the openings in the arm "43 .are substantially arcuate in form whereas the opening between these two is circular, the .arcuate openings thus, when the bolts 4! are backed away, allow-- ing for a pivotation of the arm 43 on its center bolt and a consequent adjustment due .to the arcuate slots or openings and, of course, thebolts 4! secure this auxiliary arm in any desired adjusted position. The auxiliaryarm 4.3, is for the purpose of adjustment for the relief .of tight brakes which might .occur and is hereinafter more specifically referred to.

Adjacent the upper end of theauxiliaryarm 43 there is preferably a single opening 4% and which opening may have a bearing orbushing 45 therein. This opening serves as a.means .of-securing the outer encrzl of the power arm-.21

peni 4 in the auxiliary arm 43.

The main casing 30 inwardly. of the opening 35 at one side thereof is reducedincireurnference and thus forms a shoulder "4.9.. The closure portion 3i which completes 1 the tcasin "structure includes a'g'enerally circular flange and an interior shoulder :5l,-and the :hottom thereof 50 is tapered and complemental to t e outline and tapering of the lower' portion of the main casing and is provided with an opening 59a which registers with the Scr wthreaded opening 31 in thebottom portion of the main casing, and a suitable exteriorly screw threaded bolt E serves to secure or lock or main-v tain the closure section of the casing in a fixed relationship with regard to the main portion 30 of the casing 29. The dimensions of the reduced end portion of the main casing and the shoulder formation of the cover portion .of the casing are such that when the two are telescoped together, there is provided a snug and relatively tight friction fit therebetween, and these two portions of the casing are brought together by a sliding relationship and also separated from each other by a similar, but reverse, slidin relationship. In other words, the closure p tion of the casing is merely slipped onto the reduced end portion of the main part of the casing as is clearly obvious from several fi f of the drawings such as Figs. 2, 5 and 6.

The closure portion 31' of the casing includes a curved and substantially flat lever arm 5 which, at its lower portion is substantially circular and ring-like as denoted at 53 and is provided with a centrally disposed opening 54 in the said central portion thereof, and the lever arm 52 and the circular portion, of course, are integral. The circular portion of the lever arm 52, adjacent the opening 54, has a relatively short segment 55 welded thereto, which se ment extends outwardly therefrom, the Welding being indicated at 56. This segment 55 has suitable spaced bores 51 therein, which bores are adapted to receive and support coil Spri s S, a portion of which springs project beyond the face 58 thereof and, too, this segment 55 includes a recess or aperture 59 hereinafte described in detail.

Superimposed on the lever arm 52, there is an adjustment plate 60. This plate is generally fiat and circular and includes an opening 6| which registers with opening 54 in the lever arm 52 and is of substantially the same diameter and the plate 613 has a lateral flat extension 62 integral therewith. This lateral extension has a substantially arcuate slot 63 therein and is maintained in adjusted position by means of an exteriorly screw threaded bolt 64 havin a nut 65 thereon and which bolt extends throu a circular opening 66 in the lever arm 52 and, of course, through the arcuate slot 63 .in the extension 62 of the plate 60. Another segment 61', complementing and cooperating with the first segment 55, is fixedly secured to the plate 60 as by welding 68 adjacent the openin BI, see Fig. 1'7. The segments 55 and 61 are disposed within the closure assembly of the casing, see Figs. 3, 14 and 15, and, as stated the segment 55 is fixedly secured to the lever arm 5 or the circular portion 53-thereof and this segment is relatively small as compared with the other segment 61. This segment 61 is fixedly secured to the adjusting plate 60 and both =0f the segments are adjacent the openings in the,

respective elements to which they are fixedly and permanently secured. i The lever arm 52 has an elongated slot-69 of a bolt H at one end of said bracket and the other end of the bracket 12 being bent over at may be obtained when the device is first installed on the vehicle.

.As regards the segments 55 and 6'I,it will be noted; that each of the same are undercut as at lil and, as specificallyrelating to the segment 61, this undercut formation which rests over the flange portion 15 r of the closure, serves as a means to allow this larger segment ,6! to be.

moved or rotated relative to the fixed segment 55 when, of course, the bolt64 has been loosened slightly soas to allow the plate 60, which ha the segment 61 secured thereto, to be moved by pressure on the laterally extending portion 52 or on the circular portion 60, if desired, to

thereby move the abutment end 61a, thereof toward or away from the abutment end 550. of the'segment 55 and providing for a variation of the space between these two abutments or abutting surfaces for a purpose later described.

A circular collar 16 having ratchet teeth T and 18. on opposite faces or sides thereof and constituting apdouble faced ratchet gearis afrfixed to or is integral with a cylindrical hub 19. From ,Figs. 2 and '7, it will be noted that the collar or ratchet gear 16 extends circumferentially around or about the hub 19 adjacent a short extending end thereof and'the other end 8| of the hub is relatively long as compared with the end 86. There is a circumferential groove 82 formed in the long end 8| of the hub I9 adjacent the extreme end 83 thereof and the interior of the hub isprovided with circumferentially spaced longitudinally extending splines 84 which are adapted to engage in the channels between the splines 24 at the end of the cam shaft 23. The hub 79 carrying the ratchet gear 16, it is understood, is affixed to the end of the cam' shaft by means of the complemental splines and, of course, this ratchet gear moves or otates with vthe cam shaft whenthe device is positioned thereon. The ratchet gear and the hub are disposed interiorly of the casing, as shown, and the short end extension 80 of the hub extends outwardly through the opening 32 in. the wall 33 of the main casing and the inner surface of this wall 33 has formed thereon or attached thereto a circular series of teeth 85 similar to the teeth 11 on the ratchet gear 16 and with whichzteeth 11 the teeth 85 mesh or engage and disengage at times.

" A circular ring 86 is concentrically disposed about the portion 8| of the hub I9 and this ring has a laterally extending projection 8'! extends ing from one sidep-ortion thereof, and this projection hastherein a socket or recess 88 facing toward the teeth 18 of the ratchet gear, and disposed in this socket or recess, there is a detent 89 that is normally spring urged outwardly by means of a coil spring 90, a portion of which isin' a recess 9| in the detent and another portion of which is disposed in a recess or socket 94 in the projection 81, as shown in Figures 6 and 7. The detent is of such dimensions that it is freely slidable in the said recess or socket in the projection 81 and the outer face thereof is formed with ratchet teeth 93 which are adapted to mesh or; engage; and-disengage with some of the teeth teeth 85.

pin I will enter opening 59.

Outer end portion of the stud or pin P will ride on the face portion I04 of the segment 55 and thus prevent the disengagement or unmeshing of these teeth 11 and 85, but, by the comparatively loose sliding fit between pin I05 and the 'hole'l06 in ring 86, said ring 88 with teeth 93 can disengage from and reengage with the teeth I8 on the hub at any time thus closing the space I02 in so doing.

When the adjuster is in the forward or braking stroke, the pin I05 is in position so as to prevent the teeth 1! from disengaging from With the adjuster in the released position, pin I05 is superimposed over the opening in the ring. If no brake adjustment has occurred on the previous forward or braking stroke, pin I05 does not enter hole 59 in the ring segment 55. However, if adjustment of the brakes has occurred on the previous braking stroke, teeth 1! and 85 must disengage and reengage to complete the adjusting cycle. This disengagement can now occur as, with the axial movement of the case and teeth 85 in relation to hub I9, the It will be seen that disengaging teeth 11 and 85 is prevented on the forward stroke, and if the cam shaft fails to return, the adjuster case will also remain in the forward position and will not return prematurely to cause a false brake adjustment.

The ring gear 86 as depicted in Figs. 9 through 12 has the laterally extending projection 81 integral therewith and this projection, of course, performs and is positioned between the abutments 61*- and 55 in the same manner as hereinbefore described.

The automatically operating brake adjusting devices hereinbefore described, and as shown in the drawings, operate substantially as follows: When the brakes are to 'be applied, due to the expansion of the brake shoes I8 and I9, air is introduced into the air chamber 28 and the air produces an axial movement of the power shaft 21, and this shaft being connected to the auxiliary adjustable arm 43 of the device and the device being mounted on the cam shaft 23 and ro- "tatable therewith, results in a rotation of the casing 30 of the device and the ratchet gear thus rotating the cam shaft 23 and the cam 22 carried thereby'is thus rotated or partially rotated and the brake shoes I8 and I9 are expandof the brake shoes carrying the lining thereon is terminated by the limits of expansion within oragainst the brake drum. Obviously, as the brake lining wears, the brake shoes 58 and I9 are allowed. to expand further outwardly and the cam shaft 23 and the adjusting mechanism having a further movement of rotation and the shaft 2! thus moves nearer its limit of travel. As this greater movement or limit of travel of the adjusting mechanism takes place, the wear-' ing of the lining permits the stroke of the shaft 2! to increase until it reaches a predetermined point where the adjusting cycle of the device occurs. In adjusting, the cam shaft 23 is rotated in the proper direction to tighten the 10 brakes and-the working stroke of the shaft 21 is made shorter.

The movement of the air chamber shaft 2! causes the arm 43 and the casing 30 to rotate. The end closure or wall of the casing 30 has a circular series of teeth 85 thereon and these teeth 85 being in engagement with a set of similar teeth 11 on the ratchet gear I8 thus cause the hub I9 on which the ratchet gear is mounted to rotate with the casing and the arm 63 at certain times. As already stated, this hub which carries the ratchet gear is mounted on the cam shaft and rotates or moves therewith and rotative movement of the hub on the cam shaft is prevented by the splined connection therewith. It is clear, therefore, that as the adjuster arm 43 is moved by the shaft 21, the cam shaft is rotated and the brakes are applied and, upon release of the air pressure, the air chamber shaft 2! is retracted and the adjuster and cam shaft rotate back to the starting position and, consequently, the brakeshoes carrying the brake lining collapse slightly and the brakes are released.

When the brakes are applied by expanding the brake shoes I8 and I9, the cam shaft is consequently rotated as far as the expansion of the shoes'and the lining carried thereby within the drum will permit. The ring 86 is rotated with the hub and the projection 81 moves in the space denoted at X in Figures 9 and 10 between the abutments and 6! at the ends of the segments 55 and 61 respectively.

With the brakes applied, the projection 81 or one wall thereof will be in contact with the abutshoes I8 and I9 are worn, the adjuster will rotate somewhat farther and, in this instance, the hub I9 will, of course, also rotate somewhat'farther. As the ring 86 moves'with the detent '89, as shown in Figs. 9, 10 and 11, is prevented from further rotative movement by the projection 81 thereof contacting with the abutment 6112 on the segment 61, and which abutment is held stationary, and the hub I9 rotates farther, the teeth I8 of the ratchet gear and'the teeth 93 of the detent 89 or the teeth 93 will tend to separate when the lining is worn and the adjuster advances to the point of'adjustment. In this case, the teeth93 on'the detent 89 or the teeth 93 will disengage fully from the teeth I8 of the ratchet gear on the hub and reengage with teeth I8 on'the ratchet gear, and this movement will result in the hub I9 bein rotated an amount/equal to one tooth'and in a direction in which the brakes are applied.

The hub is held in this new position and the cam shaft accordingly is rotated a like amount'and the brake shoes l8 and I9 will, therefore, bein closer adjustment with thebrake drum. -f'Upon return of the adjuster to the starting or released pOSltlOIl, the ring 86 will rotate until contact is made between the wall of the'projection 81 and the abutment 55:; at the end .of the segment '55.

As the hub I9, with the ratchet gear I6 thereon,

and the teeth 11 and I8 have been advanced in the amount of one tooth,it will be seen that they will remain in the advanced position, being held thus by the teeth 93 of detent 8901' the teeth 93* of the ring 86 in engagement with teeth-18of the ratchet gear. If the teeth "which are "within 1 l the :casing, were-to remain in engagement with teeth 11 of the ratchet gear, full return of the adjuster and the air chamber rod 2'! would be prevented. Therefore, as the hub 19 and the teeth 18 on .the ratchet gear are held imposition and'the teeth 85 are inclined to continue-to move fully intoythe released position, teeth 85 and M will disengage and the adjuster and teeth 85 will :continue to move a distance equal to one tooth at which point they will'reengage and the ad- 3 .justing cycle is completed.

The casing V3% is adapted for axial movement relative totthe cam shaft'23 and this axial movement is permitted by the space I02 between one face-of the ring 86 and the opposing face I04 of the segments 55 and 67, and thus, the springsS and S carried by the segments and the spring'90 are compressed but these'springs will urge the re- -meshing or reengagement of theteeth 93 of the detent 89 or the teeth 93 of the ring 86with the ratchet gear teeth 18 upon completion of the .adjusting cycle.

Inzcertain cases, in=the brakingstroke, the cam shaft 23 will tend to stick or bind and failto return to the original or released position and, thus, it' -is necessary to provide means for preventing the return or indexing of the adjuster mechanism or device to the released positionuntil the cam 'shaft'also returns. If the cam shaft does not return to its original position and the adjuster is permitted to return to' its originalposition, it will index one or moretimes-the same as occurs for :worn lining,.andthis false adj ustmentitherefore, wilhresultiinithe brakes being too=tight .or tight- :ened'towsuch an extent asnto prevent movement I" of thezvehicle. :To prevent-the return-of thead- -justing mechanism .oradevice when the cam shaft failsito return, :I: provide the; pin .or stud P- .or-the apinorstud-P As regards vthe pin 'TOI stud, in both -modifica- -.tions or'var-iationsof the invention, and aszshown .in Figs.5 and 9, the same'is directlyaover there- :recess .in Figs..5 and19, andin these twowsaid figures; the-.adjustingrmechanism --is in released rpositionand: disengagement of teethl'l'l: and'daiis possible. In this disengagement the space 102 betweenftheopposing faces of the ringxSG'and-the ssegments 55'and =61 is closed and-the head .of the .pin or.-stud 11?; in 'Fig. 5, .or'the extreme end of '.the

.Stl-Idfil' pin P in-Fi-g.-9,enters the recess or.open- :-in;g.5.9-in thefaceof the'segmentr55. In-Figs-B and of thedrawings, the ring 'a-fitand conse- -.quently thepinsP and P are in the advanced-pr braking-position. It is'in this braking position that indexing of teeth =l-7 anda85 must be prevented, .-.meanwhile permitting indexing of Y teeth -18-and 413 .or 19.3 .on the detentzfiasas required. :The teeth "H and t5 cannot :disengagesat :this gpointiasfthe headed :pin or .stud P or. the-stud P is met over the recess or :opening :59 in itheseg- -ment, but, "tothe contrary, is over :and engages a solid faeesect'ion or portion of the segment :55, .ythus preventing the closing the space 1112, which closing of'said'space is'necessary. in the disengagement of-teeth f't'l andi85. The'movement for disengaging and reengaging'teeth "l8 and 93"or 93 L-is-permittedby thepin'or'stud P and the recess zor opening 59,- andthistsame principle 'applies'in Figsxf: and r6 where the 'pin P moves with the ring fifiand prevents closing of the spaceliin between thefacev of this ringandthezopposedifaces =of-thersegments and-61; except in thereleased ,zposition asrshownzinzfigfi, when the :pin is rli- .rectly1 opposite; and; eventually the :endthereof is .in the recessor opening .59.

The space :R beneath the lower tend of the :de- 'tent:89 and the lower walloftherecess 8'! in the projection permits disengagement of thistoothed vdetent from theteeth'lfl of .the ratchet gear.

-When the adjuster is installed-on the vehicle, andpreparations are made to attach the anchor strap-or supporting bracket 10 and secure this bracket lay-means of the bolt and nut H to the lever arm 52, this arm 52 is moved rotatively in .thezsame-direction as the braking strokeasifar as its .free movement-willpermit, and issecured =in that-position. This-results in moving the seg- -ment -61 .forward 'and the abutment 6'! thereof is fin contact with the projection 81 on the ring -85. This results in timing .the'adjustingcycle, which is necessary, otherwise the adjusting 'could possibly attempt to .occur during the braking stroke and could not'be completed because the working partsof the device arenaturallyunder .strain during the braking stroke. This timing is necessary ior the eflicient operation-of-the radjuster mechanism. It is understood that the :slot 159 in "the arm 52 enables the device to be properly attached to the sup- .por'ting bracket Hi-and, further, that inlieuzoif the supporting bracket Many other mean-s :for supporting or attaching the lever arm to the vehicle "may "be utilized.

It is to be understood that the dimensions-of th'e'peripheries of the :ratchet gear 15 and the ring gear 86- and thesegments T55 and .6! are-such that'there .is'a slight clearance betweenthe same and the interior'adjacent wall of 'the main casingso as to allow the proper movement of these elements within and relative to 'the'casing, such movement being either rotative 'or axial. In other words, the tolerances of 'these elements within'th'e casing with regard to the diameter of the 'interior t'hereof rare :such that the .elements and the casing-will be allowed their proper movements as hereinbefore described.

In both modifications of the invention, the dimensions of the space I02 is such'that simultaneous disengagement of'the'cooperating sets of gear "teeth $5, ll and '78, 93 or 18, 93 is prevented. 'In other words, attno time can both-o1 the aforesaid sets of teeth be disengaged or unmeshed, assuming, of course, the component elements are disposed and maintained in the casing and in their cooperating and operative relationship therein.

The device 'operatesthe brakes of the vehicle 'in'the'normal'operation of such brakes, and also automatically adjusts the brakes, as hereinbefore explained.

.I claim:

.1. A fully automatically operating slack adjusting-device comprising-a two-part hollow casing, an elongated hub carrying a circumferential ratchet gearwith teeth on opposite side faces thereof disposed in theca-sing, the casing having .end wallsformed with centrally disposed aligned openings through which respective end portions of the hub rotatably fit, the hub being adapted tobe positioned about an end portion of a shaft andfixecl'thereon to turn'therewith, the casing having a series of teeth integral with one end wall thereof and arranged in a circular path concentric with the opening therein and which teeth are adapted to mesh with and disengage from the-teeth on the confronting side face of the ratchet gear, a ring gear fitting loosely about said'hub concentric therewith and disposed within the-casing at-the opposite side of the ratchet gearfmmLthe .toothed end wall of the casing, said ring gear having a side face formed with teeth that are adapted to mesh with and be disengaged from the teeth on the confronting side face of the ratchet gear, spaced segments disposed in said casing and having a yieldable cooperation with the ring gear, one of the segments being rigid with an adjusting place rotatably mounted for turning movement in the casing and about the hub to adjusted positions, said segment having spaced ends and being rotatable about the hub with the adjusting plates to adjusted positions, the other segment being stationarily mounted within the casing and located in the space between ends of the adjustable segment and being of appreciably less length than the space into which it fits, confronting faces at ends of the segments constituting abutments limiting movement of the adjustable segment, the ring gear having an integral projection thereon and which projection is disposed in the space between the abutments, and a member carried by the ring gear and adapted to cooperate with the fixed segment for preventing the adjusting cycle of the brake adjusting mechanism when the hub and the cam shaft are in the braking position.

2. A slack adjuster as defined in and by claim 1 wherein an adjusting member is rotatably mounted exteriorly of and closely adjacent the casing, the adjustable segment being rigid with said adjusting member and movable thereby to adjusted positions relative to the stationary segment upon movement of said adjusting member.

3. A fully automatic slack adjusting device adapted to be attached to the end of a cam shaft,

said device comprising a substantially hollow casing and a detachable closure for one end thereof, the other end of the casing having a head and a series of teeth carried thereby within the casing and arranged in a circular path concentric with the casing, an elongated cylindrical hub disposed in rotative relationship within the casing and having the opposite ends thereof extending through and beyond the head of the casing and the closure for the casing, the hub being adapted to be mounted on an end of a cam shaft to turn therewith and carrying a circumferential ratchet gear with teeth on opposite side faces thereof, a ring gear of substantially the same circumferential dimensions as the ratchet gear loosely mounted about the hub at r the opposite side of the rachet gear from the head of the casing and having a side formed with teeth adapted to mesh with the teeth on the confronting side face of the ratchet gear, the teeth on the other face of the ratchet gear being adapted to engage the teeth carried by the head of the casing, a pair of segments also concentrically disposed about the hub within the casing and located between the ring gear and the closure for the casing, spring means interposed between the segments and the confronting side face of the ring gear to normally urge the latter into meshed relationship with the ratchet gear, one of the segments being disposed between spaced ends of the other and of a length appreciably less than that of the space in which it fits and permitting movement of one segment relative to the other to adjusted positions, each segment having opposed end faces which constitute abutments and limit movement of the movable segment relative to the other segment, the ring gear having a laterally extending projection integral therewith and which projection is disposed in the space between the abutments of the two segments, means exteriorly of the casing but in close relationship therewith and fixedly connected with the movable segment within the casing so that this said segment may be moved toward or away from ends of the other segment which is stationary and thus vary the space between the abutments at the ends of the segments, whereby the movement of the device and the projection extending into space between the abutments may be varied to effect the proper adjustment of the slack.

4. A slack adjusting device as defined in and by claim 3 wherein a stud is carried by the ring gear member and which stud projects beyond one side face of this ring gear and prevents indeXing of the gear teeth of the ratchet gear and the ring gear under unsatisfactory conditions but which allows for indexing and adjustment automatically of the slack when adjustment of slack is necessary.

5. A fully automatic slack adjusting device comprising a hollow two-part casing, one of which parts thereof serves as a closure for the other part, and companion ratcheting toothed members capable of meshing and unmeshing with each other disposed Within the hollow casing, an operating shaft to which one of which members is adapted to be attached and move therewith, the casing having a laterally extending integral arm to which an adjustable auxiliary arm is ivotally connected by releasable fastener means permitting the auxiliary arm to be tilted to an adjusted position relative to the arm of the easing and releasably secured in the adjusted position.

6. A slack adjusting device as defined in and by claim 5 wherein the auxiliary arm is pivotally attached to the stationary arm of the casing and has arcuate openings therein, and bolts carried by the stationary arm and extending through the arcuate openings for maintain ing the auxiliary arm in any predetermined adjusted position relative to the stationary arm.

KIRKLAND B. MacDOUG-ALL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,156,154 Hooker Apr. 25, 1939 2,347,186 Freeman Apr. 25, 1944 2,385,621 Freeman Sept. '25, 1945 2,481,319 MacDougall Sept. 6, 1949 2,522,903 Shively Sept. 19, 1950 

